Stabilizer compositions

ABSTRACT

Stabilizer compositions comprise phosphate of the formula I or II, a phosphite of the formula III, and a phenol of the formula IV as these formulas are defined herein. The stabilizer compositions are useful for stabilizing polymers. Methods for making stabilized polymer compositions involve intermixing the stabilizer compositions and the polymers, e.g., by extruding, pelletizing, and/or molding.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.12/300,686, filed Dec. 16, 2008 (allowed), which is a U.S. NationalPhase entry of International Application No. PCT/US2007/011342, filedMay 10, 2007, which claims benefit of priority from U.S. ProvisionalApplication No. 60/747,459, filed May 17, 2006, each of which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to blends of phosphites and phenols and the useof such blends as stabilizers for polymers.

2. Description of the Related Art

A wide range of stabilizers are added to polymers to reduce thedetrimental effects of various environments on polymer properties. Thestabilizers may be added to the polymers to stabilize them againstvarious sources of degradation such as heat, light, oxygen, mechanicalstress and the presence of impurities, any or all of which may beencountered during polymer preparation, storage, shipping, fabricationinto useful articles and/or during the ultimate use of those articles.Many polymer degradation pathways are believed to result from thepresence of free radicals created in the polymers by, e.g., exposure toheat, ultraviolet radiation, mechanical shear, and/or impurities. It isbelieved that when a free radical is formed, abstraction of a hydrogenatom from the polymer can initiate a chain reaction that results inpolymer oxidation. Subsequent reaction of the radical with an oxygenmolecule can yield a peroxy radical, which then can react with anavailable hydrogen atom to form an unstable hydroperoxide and anotherfree radical. In the absence of polymer stabilizers, these reactions canbecome self-propagating and can lead to polymer degradation andundesirable reduction in properties.

Antioxidants are polymer additives that are used to reduce oxidativedegradation of polymers. Phenolic antioxidants are a commerciallysignificant class of antioxidants in which the phenolic hydroxyl groupis flanked by alkyl or arylalkyl groups. The flanking groups providesteric hindrance around the oxygen atom, thereby influencing theperformance of the antioxidant. Greater steric hindrance has generallybeen associated with greater antioxidant activity, and thus in a numberof commercially significant phenolic antioxidants the phenolic hydroxylgroup is flanked on both sides by relatively large groups. For example,phenolic antioxidants have traditionally been based on structuressimilar to 2,6-di-t-butyl-4-methylphenol (BHT), in which t-butyl groupssymmetrically flank the phenolic hydroxyl group.

Phosphite antioxidants are another commercially significant class ofantioxidants. Examples include (bis-(2,4-dicumylphenyl)pentaerythritoldiphosphite (DOVERPHOS® S-9228) and tris-(2,4-di-t-butylphenyl)phosphite (IRGANOX® 168). A blend containing 64.1% CYASORB® UV-3529(1,6-hexanediamine, N,N′-bis(1,2,2,6,6-pentamethyl)-4-piperidinyl)-,polymers with 2,4-dichloro-6-(4-morpholinyl)-1,3,5-triazine), 7.7%CYANOX® 1790 (1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione), 14.5% IRGAPHOS® 168(tris-(2,4-di-t-butylphenyl)phosphite), 7.7% ULTRANOX® 626(bis-(2,4-di-t-butylphenyl) pentaerythritol diphosphite) and 5.1% KADOX®911 (Zinc Oxide) was apparently sold commercially in 2002. TheDOVERPHOS® S-9228, IRGANOX® 168 and ULTRANOX® 626 products are generallyconsidered to be non-symmetrically hindered because the groups flankingthe oxygen atom that is attached to the aromatic ring are different fromone another.

U.S. Pat. No. 6,770,693 and U.S. Patent Publication No. 2005/0113494disclose blends of phosphites and hindered phenols as polymerstabilizers. The exemplified blends included a non-symmetricallyhindered phosphite (such as DOVERPHOS® S-9228) and a symmetricallyhindered phenol (such as tetrakis [methylene(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)]methane). For blendscontaining a second phosphite, the optimum ratio of DOVERPHOS S-9228 tothe second phosphite was apparently greater than one, indicating thatthe DOVERPHOS® S-9228 drove the performance of these blends.

There is a need for improved polymer stabilizers, polymer compositionsthat include such stabilizers, and methods of making such polymercompositions.

SUMMARY OF THE INVENTION

In an aspect, the preferred embodiments of the present invention providea stabilizer composition. The stabilizer composition comprises ahindered arylalkyl phosphite of the formula (I) or (II),

where R¹ and R⁵ together comprise at least 5 carbons, where R⁶ and R¹⁰together comprise at least 5 carbons, where R¹¹ and R¹⁵ togethercomprise at least 5 carbons, and where R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸,R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, X and Y are each individually selectedfrom hydrogen, C₁-C₁₂ alkyl, C₃-C₁₂ cycloalkyl, C₄-C₁₂ alkyl cycloalkyl,C₆-C₁₀ aryl, and C₇-C₁₂ alkylaryl. In a preferred embodiment, at leastone of R¹ and R⁵ comprises a tertiary carbon, at least one of R⁶ and R¹⁰comprises a tertiary carbon, and/or at least one of R¹¹ and R¹⁵comprises a tertiary carbon. The composition further comprises atrisarylphosphite of the formula (III),

where R¹⁶, R¹⁷, R¹⁸, R¹⁹, and R²⁰ are each individually selected fromhydrogen, C₁-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₄-C₂₀ alkyl cycloalkyl,C₆-C₁₀ aryl, and C₇-C₂₀ alkylaryl. The composition further comprises ahindered phenol comprising a molecular fragment selected from formulas(IVa), (IVb) and (IVc),

where R²¹ is selected from hydrogen and C₁₋₃ alkyl and where R₂₂ and R₂₃are each individually selected from hydrogen, C₁-C₂₀ alkyl, C₃-C₂₀cycloalkyl, C₄-C₂₀ alkyl cycloalkyl, C₆-C₁₀ aryl, and C₇-C₂₀ alkylaryl.Hindered phenols comprising a molecular fragment selected from formulas(IVa), (IVb) and (IVc) may be referred to collectively herein ascompounds of the formula (IV).

In an aspect, the preferred embodiments of the present invention providea polymer composition. The polymer composition comprises a polymer and astabilizing amount of a stabilizer composition. The stabilizercomposition comprises a hindered arylalkyl phosphite of the formula (I)or (II), a trisarylphosphite of the formula (III), and a hindered phenolcomprising a molecular fragment selected from formulas (IVa), (IVb) and(IVc), as described above.

In an aspect, the preferred embodiments of the present invention providea polymer composition, comprising a polyolefin and apolyolefin-stabilizing amount of a hindered arylalkyl phosphite selectedfrom 2-butyl-2-ethyl-1,3-propanediol 2,4,6-tri-t-butylphenol phosphite(ULTRANOX® 641), bis-(2,6-di-t-butyl-4-methlphenyl) pentaerythritoldiphosphite (ADK Stabilizer PEP 36),(bis-(2,4-dicumylphenyl)pentaerythritol diphosphite (DOVERPHOS® 9228),2-butyl-2-ethyl-1,3-propanediol 2,4-di-cumylphenol phosphite,2-butyl-2-ethyl-1,3-propanediol 4-methyl-2,6-di-t-butylphenol phosphite,and bis-(2,4,6-tri-t-butyl-phenyl) pentaerythritol diphosphite. Thepolymer composition further comprises a polyolefin-stabilizing amount ofa trisarylphosphite selected from tris-(2,4-di-t-butylphenyl) phosphite(IRGANOX® 168), tris(4-nonylphenyl phosphite (TNPP) and triphenylphosphite (DOVERPHOS® 10). The polymer composition additionallycomprises a polyolefin-stabilizing amount of a hindered phenol selectedfrom (1,3,5-Tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione(CYANOX® 1790), 1,1,3-Tris(2′-methyl-4′-hydroxy-5′-t-butylphenyl)butane,Triethylene glycol bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate](IRGANOX® 245), 4,4′-Thiobis (2-t-butyl-5-methylphenol),2,2′-Thiodiethylenebis[3-(3-t-butyl-4-hydroxyl-5-methylphenyl)propionate], Octadecyl3-(3′-t-butyl-4′-hydroxy-5′-methylphenyl)propionate,Tetrakismethylene(3-t-butyl-4-hydroxy-5-methylhydrocinnamate)methane,N,N′-Hexamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionamide], andDi(4-tertiarybutyl-3-hydroxy-2,6-dimethyl benzyl) thiodipropionate.

In an aspect, the preferred embodiments of the present invention providea process for making a stabilized polymer composition. The processcomprises mixing a polymer with a stabilizing amount of a stabilizercomposition. The stabilizer composition comprises a hindered arylalkylphosphite of the formula (I) or (II), a trisarylphosphite of the formula(III), and a hindered phenol comprising a molecular fragment selectedfrom formulas (IVa), (IVb) and (IVc), as described above.

These and other aspects and embodiments are described in greater detailbelow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has been discovered that antioxidant stabilizer blends of an aryldialkyl phosphite and a trisarylphosphite demonstrate unexpectedbenefits when used in combination with at least one phenol antioxidanthaving reduced hindrance about the phenolic oxygen, as compared tohighly hindered phenols more typically used in such applications. Forexample, in an embodiment, the phenol antioxidant is a non-symmetricallyhindered phenol in which the phenolic oxygen is flanked by a t-butylgroup and a hydrogen or C₁₋₃ alkyl group. The aryl dialkyl phosphite inthe blend is preferably significantly hindered about the oxygen atomthat is attached to the aromatic ring. For example, in an embodiment, atleast one of the groups flanking the oxygen atom that is attached to thearomatic ring of the aryl dialkyl phosphite is a group that comprises atertiary carbon, such as a tertiary alkyl group or a cumyl group, andthe groups flanking the oxygen atom together preferably comprise atleast five carbons, more preferably at least eight carbons.Surprisingly, in antioxidant stabilizer blends of an aryl dialkylphosphite and a trisarylphosphite in combination with a reducedhindrance phenol, relatively greater hindrance is preferred about theoxygen atom that is attached to the aromatic ring of the aryl dialkylphosphite, as compared to aryl dialkyl phosphites typically used in suchapplications.

It has been further discovered in preferred stabilizer blends thatratios of trisarylphosphite to aryl dialkyl phosphites greater than oneprovide improved performance. Compared to similar stabilizer blendsutilizing a more highly hindered phenol antioxidant, and/or a lesshindered aryl dialkyl phosphite, preferred blends provide betterprotection against polymer degradation during processing as evidenced byreduced discoloration during compounding, reduced discoloration duringlow shear, long residence time thermally induced sintering processes,such as rotational molding, and/or reduced changes in melt flow afterhigh temperature exposure in an oxygen rich environment. Embodiments ofthe present invention provide significant advantages over previousblends, including current commercially available additive blends.

Stabilizer Compositions

In an embodiment, a stabilizer composition comprises a hinderedarylalkyl phosphite of the formula (I) or (II); a trisarylphosphite ofthe formula (III); and a hindered phenol comprising a molecular fragmentselected from formulas (IVa), (IVb) and (IVc), each as set forth above.In an embodiment of the stabilizer composition, R¹ and R⁵ togethercomprise at least 8 carbons, R⁶ and R¹⁰ together comprise at least 8carbons, and/or R¹¹ and R¹⁵ together comprise at least 8 carbons. Inanother embodiment of the stabilizer composition, R¹, R⁶ and/or R¹¹ isH. In a further embodiment of the stabilizer composition, R⁵, R¹⁰ and/orR¹⁵ is cumyl. In another embodiment of the stabilizer composition, R²¹is methyl.

In another embodiment of the stabilizer composition, the hinderedarylalkyl phosphite is selected from 2-butyl-2-ethyl-1,3-propanediol2,4,6-tri-t-butylphenol phosphite,bis-(2,6-di-t-butyl-4-methlphenyl)pentaerythritol diphosphite,(bis-(2,4-dicumylphenyl)pentaerythritol diphosphite,2-butyl-2-ethyl-1,3-propanediol 2,4-di-cumylphenol phosphite,2-butyl-2-ethyl-1,3-propanediol 4-methyl-2,6-di-t-butylphenol phosphite,and bis-(2,4,6-tri-t-butyl-phenyl)pentaerythritol diphosphite.

In another embodiment of the stabilizer composition, thetrisarylphosphite is selected from tris-(2,4-di-t-butylphenyl)phosphite, tris(4-nonylphenyl phosphite, and triphenyl phosphite.

In another embodiment of the stabilizer composition, the hindered phenolis selected from(1,3,5-Tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H, 5H)-trione, 1,1,3-Tris(2′-methyl-4′-hydroxy-5′-t-butylphenyl)butane,Triethylene glycolbis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate], 4,4′-Thiobis(2-t-butyl-5-methylphenol), 2,2′-Thiodiethylenebis[3-(3-t-butyl-4-hydroxyl-5-methylphenyl)propionate], Octadecyl3-(3′-t-butyl-4′-hydroxy-5′-methylphenyl)propionate,Tetrakismethylene(3-t-butyl-4-hydroxy-5-methylhydrocinnamate)methane,N,N′-Hexamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionamide], andDi(4-tertiarybutyl-3-hydroxy-2,6-dimethyl benzyl) thiodipropionate.

Embodiments of the hindered phenols described above are substantiallyless hindered than antioxidant phenols which are conventionally utilizedin antioxidant compositions, owing to the generally smaller groupsflanking the phenolic oxygen. As discussed in greater detail below,embodiments of the stabilizer compositions utilized in polymercompositions provide unexpectedly beneficial properties to the polymercompositions, such as improved color and/or impact strength.

In an embodiment of the stabilizer composition, it has been discoveredthat certain proportions of the arylalkyl phosphites to thetrisarylphosphites provide improved stabilizer performance. For example,in an embodiment, the weight ratio of the hindered arylalkyl phosphiteto the trisarylphosphite is less than one, e.g., the weight ratio of thehindered arylalkyl phosphite to the trisarylphosphite is in the range offrom about 1:15 to about 4:5, preferably in the range of from about 1:10to about 2:3.

The amounts of each of the components of the stabilizer compositions mayvary over a broad range, e.g., the stabilizer composition may comprisefrom about 0.01% to about 99.99% of the hindered arylalkyl phosphite ofthe formula (I) or (II), from about 0.01% to about 99.99% of thetrisarylphosphite of the formula (III), and from about 0.01% to about99.99% of the hindered phenol comprising a molecular fragment selectedfrom formulas (IVa), (IVb) and (IVc), each by weight based on totalstabilizer composition weight. It will be understood that the amounts ofeach of the aforementioned three components of the stabilizercomposition may be adjusted relative to one another so that the total ofthe three components is 100%, or the stabilizer composition may containone or more additional components (such as a polymer, HALS and/orultraviolet light absorber as described below), in which case the totalamount of the aforementioned three components in the stabilizercomposition is less than 100%.

Polymer Compositions and Processes for Making Them

Embodiments of the present invention also provide polymer compositionsand processes for making them, e.g., by intermixing a stabilizercomposition as described herein with a polymer to produce a stabilizedpolymer composition. In certain embodiments, these stabilized polymercompositions are suitable for use in conjunction with rotational moldingtechniques to form molded parts.

In a preferred embodiment, a stabilizer composition suitable forintermixing with a polymer comprises a polymer stabilizing amount of ahindered arylalkyl phosphite of the formula (I) or (II), a polymerstabilizing amount of a trisarylphosphite of the formula (III), and apolymer stabilizing amount of a hindered phenol comprising a molecularfragment selected from formulas (IVa), (IVb) and (IVc), as describedabove. The stabilizing amount of the stabilizer composition in thepolymer composition may vary over a broad range as determined by routineexperimentation, and is typically in the range of from about 0.001% toabout 5%, preferably in the range of from about 0.01% to about 1.0%, byweight based on the total weight of the polymer composition. In anembodiment, the hindered arylalkyl phosphite of the formula (I) or (II)and the trisarylphosphite of the formula (III) are together present inthe polymer composition in a total phosphite amount in the range ofabout 0.01 wt. % to about 1.0 wt %, preferably in the range of about0.02 wt. % to about 0.5 wt %, based on total polymer composition weight.In an embodiment, the amount of the hindered arylalkyl phosphiteutilized in the polymer composition is less than the amount of thetrisarylphosphite on a weight basis. In an embodiment, the hinderedphenol comprising a molecular fragment selected from formulas (IVa),(IVb) and (IVc) is present in the polymer composition in an amount inthe range of about 0.01 wt. % to about 1.0 wt %, preferably in the rangeof about 0.02 wt. % to about 0.5 wt %, based on total polymercomposition weight.

In an embodiment of the polymer composition, the hindered arylalkylphosphite is selected from 2-butyl-2-ethyl-1,3-propanediol2,4,6-tri-t-butylphenol phosphite,bis-(2,6-di-t-butyl-4-methlphenyl)pentaerythritol diphosphite,(bis-(2,4-dicumylphenyl)pentaerythritol diphosphite,2-butyl-2-ethyl-1,3-propanediol 2,4-di-cumylphenol phosphite,2-butyl-2-ethyl-1,3-propanediol 4-methyl-2,6-di-t-butylphenol phosphite,and bis-(2,4,6-tri-t-butyl-phenyl)pentaerythritol diphosphite.

In another embodiment of the polymer composition, the trisarylphosphiteis selected from tris-(2,4-di-t-butylphenyl) phosphite,tris(4-nonylphenyl phosphite (TNPP) and triphenyl phosphite.

In another embodiment of the polymer composition, the hindered phenol isselected from (1,3,5-Tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione,1,1,3-Tris(2′-methyl-4′-hydroxy-5′-t-butylphenyl)butane, Triethyleneglycol bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate],4,4′-Thiobis (2-t-butyl-5-methylphenol), 2,2′-Thiodiethylenebis[3-(3-t-butyl-4-hydroxyl-5-methylphenyl)propionate], Octadecyl3-(3′-t-butyl-4′-hydroxy-5′-methylphenyl)propionate,Tetrakismethylene(3-t-butyl-4-hydroxy-5-methylhydrocinnamate)methane,N,N′-Hexamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionamide], andDi(4-tertiarybutyl-3-hydroxy-2,6-dimethyl benzyl)thiodipropionate.

In an embodiment, a process for making a stabilized polymer compositioncomprises mixing a polymer and a stabilizing amount of a stabilizercomposition as described herein. In a preferred embodiment, thestabilizing amount of the stabilizer composition is an amount that iseffective to reduce yellowing. In certain embodiments, the processcomprises intermixing about 0.01 wt % to about 1.0 wt %, preferablyabout 0.02 wt % to about 0.5 wt % of the stabilizer composition with thepolymer, by weight based on total amount of the resulting polymercomposition. It will be understood that the components may be intermixedin any manner, e.g., singly, in portions, pre-mixed, etc. For example,in an embodiment, the stabilizer composition is formed in the presenceof the polymer, e.g., by adding at least a portion of at least one ofthe hindered arylalkyl phosphite of the formula (I) or (II), thetrisarylphosphite of the formula (III), and the hindered phenolcomprising a molecular fragment selected from formulas (IVa), (IVb) and(IVc), to the polymer separately from at least a portion of theremainder of the other components of the stabilizer composition.

The components of the stabilized polymer composition may be mixed in anyorder. In an embodiment, the mixing comprises at least one techniqueselected from extruding, pelletizing, and molding. In a furtherembodiment, the molding comprises at least one technique selected fromblow molding, injection molding, and rotational molding. In alternativeembodiments, mixing may be carried out by a process that comprises atleast one of melting, dissolution in a solvent, and dry mixing.

In an embodiment, the polymer composition described above (e.g.,comprising a hindered arylalkyl phosphite of the formula (I) or (II); atrisarylphosphite of the formula (III); and a hindered phenol comprisinga molecular fragment selected from formulas (IVa), (IVb) and (IVc))further comprises a light stabilizer, such as a hindered amine lightstabilizer (HALS), a hindered hydroxyl benzoate, a nickel phenolateand/or an ultraviolet light absorber (UVA). The light stabilizer may bea mixture, e.g., the light-stabilized polymer composition may comprise aHALS and a UVA. A light-stabilized polymer composition preferablycomprises a light-stabilizing amount of the light stabilizer, e.g., anamount of light stabilizer that stabilizes the polymer compositionagainst the degradative effects of visible and/or ultraviolet radiation,as determined by routine experimentation.

In an embodiment, the polymer composition described above (e.g.,comprising a hindered arylalkyl phosphite of the formula (I) or (II); atrisarylphosphite of the formula (III); and a hindered phenol comprisinga molecular fragment selected from formulas (IVa), (IVb) and (IVc))further comprises a light-stabilizing amount of a HALS. The amount ofHALS in such a light-stabilized polymer composition is preferably in therange of about 0.01 wt. % to about 1.0 wt %, preferably in the range ofabout 0.02 wt. % to about 0.5 wt %, based on total polymer compositionweight. Such a polymer composition may be prepared by intermixing thecomponents in the general manner described above. For example, in anembodiment, a process for forming a polymer composition comprises mixingthe polymer, a stabilizer composition as described above and alight-stabilizing amount of the HALS. In an embodiment, the HALScomprises a molecular fragment of the formula (V),

Where R²⁴, R²⁵, R²⁶, and R²⁷ are each individually selected fromhydrogen, C₁-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₄-C₂₀ alkyl cycloalkyl,C₆-C₁₀ aryl, and C₇-C₂₀ alkylaryl; and where R²⁸ is selected fromhydrogen, C₁-C₂₀ alkyl, C₁-C₂₀ acyl and C₁-C₂₀ alkoxyl.

In a preferred embodiment, the HALS included in the composition orutilized in the process for making it is selected frombis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate;bis(2,2,6,6-tetramethylpiperidin-4-yl)succinate;bis(1,2,2,6,6-pentamethylpiperidin-4-yl)sebacate;bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate;bis(1,2,2,6,6-pentamethylpiperidin-4-yl) n-butyl3,5-di-tert-butyl-4-hydroxybenzylmalonate; a condensate of1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinicacid; 2,2,6,6-tetramethylpiperidin-4-yl stearate;2,2,6,6-tetramethylpiperidin-4-yl dodecanate;1,2,2,6,6-pentamethylpiperidin-4-yl stearate;1,2,2,6,6-pentamethylpiperidin-4-yl dodecanate; a condensate ofN,N′-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine and4-tert-octylamino-2,6-dichloro-1,3,5-triazine; tris(2,2,6,6-tetramethylpiperidin-4-yl) nitrilotriacetate;tetrakis(2,2,6,6-tetramethylpiperidin-4-yl)-1,2,3,4-butanetetracarboxylate;4-benzoyl-2,2,6,6-tetramethylpiperidine;4-stearyloxy-2,2,6,6-tetramethylpiperidine;bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate;3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione;bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate;bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)succinate; a condensate ofN,N′-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine and4-morpholino-2,6-dichloro-1,3,5-triazine; a condensate of2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazineand 1,2-bis(3-aminopropylamino)ethane; a condensate of2-chloro-4,6-bis(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazineand 1,2-bis-(3-aminopropylamino)ethane;8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione;3-dodecyl-1-(2,2,6,6-tetramethylpiperidin-4-yl)pyrrolidin-2,5-dione;3-dodecyl-1-(1-ethanoyl-2,2,6,6-tetramethylpiperidin-4-yl)pyrrolidin-2,5-dione;3-dodecyl-1-(1,2,2,6,6-pentamethylpiperidin-4-yl)pyrrolidine-2,5-dione;a mixture of 4-hexadecyloxy- and4-stearyloxy-2,2,6,6-tetramethylpiperidine; a condensate ofN,N′-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine and4-cyclohexylamino-2,6-dichloro-1,3,5-triazine; a condensate of1,2-bis(3-aminopropylamino)ethane, 2,4,6-trichloro-1,3,5-triazine and4-butylamino-2,2,6,6-tetramethylpiperidine;2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decane;oxo-piperanzinyl-triazines and a reaction product of7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decaneand epichlorohydrin.

In an embodiment, the polymer composition described above (e.g.,comprising a hindered arylalkyl phosphite of the formula (I) or (II); atrisarylphosphite of the formula (III); and a hindered phenol comprisinga molecular fragment selected from formulas (IVa), (IVb) and (IVc))further comprises a light-stabilizing amount of a UVA. Such a polymercomposition preferably comprises an ultraviolet-light absorbing amountof the UVA, e.g., an amount of UVA that alone or in combination with asecond light stabilizer (e.g., a HALS) stabilizes the polymercomposition against the degradative effects of ultraviolet radiation, asdetermined by routine experimentation. When used without a second lightstabilizer, e.g., in the absence of a HALS, the amount of UVA in thepolymer composition is preferably in the range of about 0.025 wt. % toabout 2.5 wt. %, based on total polymer composition weight. When used incombination with a light-stabilizing amount of a HALS, the amount of UVAin the polymer composition is preferably in the range of about 0.001 wt.% to about 1.0 wt %, more preferably in the range of about 0.002 wt. %to about 0.5 wt %, based on total polymer composition weight. Suchpolymer compositions may be prepared by intermixing the components inthe general manner described above. For example, in an embodiment, aprocess for forming a polymer composition comprises mixing the polymerand a stabilizer composition as described above (optionally including alight-stabilizing amount of a HALS) with a light-absorbing amount of anultraviolet light absorber selected from a 2-hydroxybenzophenone, a2-(2′-hydroxyphenyl)benzotriazole, and a2-(2′-hydroxyphenyl)-1,3,5-triazine. In a preferred embodiment of thecomposition or the process for making it, the UVA is a2-(2′-hydroxyphenyl)-1,3,5-triazine of the formula (VI),

where R²⁹ and R³⁰ are each individually selected from C₆-C₁₀ aryl,C₁-C₁₀ alkyl-substituted amino, C₁-C₁₀ acyl and C₁-C₁₀ alkoxyl; and R³¹,R³², R³³ and R³⁴ are each individually selected from hydrogen, hydroxyl,C₁-C₁₀ alkyl, C₁-C₁₀ alkoxyl, C₁-C₁₀ acyl, C₃-C₁₂ cycloalkyl, C₄-C₁₂alkyl cycloalkyl, C₆-C₁₀ aryl, and C₇-C₁₂ alkylaryl.

In an embodiment, the polymer composition described above (e.g.,comprising a hindered arylalkyl phosphite of the formula (I) or (II); atrisarylphosphite of the formula (III); and a hindered phenol comprisinga molecular fragment selected from formulas (IVa), (IVb) and (IVc))further comprises a light-stabilizing amount of a hindered hydroxylbenzoate. Examples of hindered hydroxyl benzoates that may beincorporated into the polymer composition or used in the process formaking it include those described in U.S. Pat. No. 6,843,939, which ishereby incorporated by reference in its entirety, and particularly forthe purpose of describing hindered hydroxyl benzoates. The amount ofhindered hydroxyl benzoate in the polymer composition is preferably inthe range of about 0.001 wt. % to about 3.0 wt %, more preferably in therange of about 0.01 wt. % to about 2.0 wt %, based on total polymercomposition weight. Such polymer compositions may be prepared byintermixing the components in the general manner described above.

In an embodiment, the polymer composition described above (e.g.,comprising a hindered arylalkyl phosphite of the formula (I) or (II); atrisarylphosphite of the formula (III); and a hindered phenol comprisinga molecular fragment selected from formulas (IVa), (IVb) and (IVc))further comprises a light-stabilizing amount of a nickel quencher, e.g.,a nickel phenolate. A variety of nickel quenchers are known to thoseskilled in the art and include those that are widely used inagricultural film applications where they are valued for theirresistance to deactivation by agricultural chemicals. Examples of nickelquenchers that may be incorporated into the polymer composition or usedin the process for making it include those described in U.S. Pat. Nos.3,215,707 and 3,218,294, both of which are hereby incorporated byreference in their entireties, and particularly for the purpose ofdescribing nickel quenchers. The amount of nickel quencher in thepolymer composition is preferably in the range of about 0.001 wt. % toabout 2.0 wt %, more preferably in the range of about 0.005 wt. % toabout 1.0 wt %, based on total polymer composition weight. Such polymercompositions may be prepared by intermixing the components in thegeneral manner described above.

In a preferred embodiment, the polymer comprises a polyolefin althoughit is envisioned that embodiments of the process may be directed topolymer compositions comprising other polymers as well.

The term “polyolefin” is used herein in its ordinary sense as known tothose skilled in the art and includes homopolymers as well as copolymersof olefinic compounds. Typically, polyolefin homopolymers comprise thepolymerization products of mono-1-olefins having about 2 to about 10carbon atoms per molecule, preferably, about 2 to about 6 carbon atomsper molecule. Exemplary mono-1-olefins, which produce polyolefins havingdesirable properties, include, but are not limited to, ethylene,propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene. In anembodiment, the mono-1-olefin is ethylene and the resulting polymer ispolyethylene (e.g., high density polyethylene). Suitable polyolefincopolymers comprise at least 2 different mono-1-olefins, a monomer andone or more co-monomers, each having from about 2 to about 16 carbonatoms per molecule. Preferably the monomers include, but are not limitedto, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, and 1-octene.Exemplary comonomers include, but are not limited to, aliphatic1-olefins, such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene,1-hexene, 1-octene, and other higher olefins and conjugated ornon-conjugated diolefins such as 1,3-butadiene, isoprene, piperylene,2,3-dimethyl-1,3-butadiene, 1,4-pentadiene, 1,7-hexadiene, and othersuch diolefins and mixtures thereof. Linear low density polyethylene(LLDPE) is a preferred copolymer that is made by a process thatcomprises copolymerizing ethylene and small amounts of a higheralpha-olefin comonomer having from about 3 to about 16 carbon atoms permolecule.

EXAMPLES

The following examples are provided to assist one skilled in the art tofurther understand embodiments of the present invention. These examplesare intended for illustration purposes but are not to be construed aslimiting the scope of the embodiments of the present invention.

Chemical compounds utilized in these examples (summarized below) areobtained from commercial sources or prepared by known methods:

Phosphite Antioxidants:

P1. (tris-(2,4-di-t-butylphenyl)phosphite) (IRGAPHOS® 168):

P2. (bis-(2,4-dicumylphenyl)pentaerythritol diphosphite (DOVERPHOS®9228):

P3. bis-(2,4-di-t-butylphenyl) pentaerythritol diphosphite (Ultranox626):

P4. 2-butyl-2-ethyl-1,3-propanediol 2,4,6-tri-t-butylphenol phosphate(ULTRANOX® 641):

P5. bis-(2,6-di-t-butyl-4-methlphenyl) pentaerythritol diphosphite (ADKPEP 36):

P6. Tris(4-n-nonylphenyl) phosphite (TNPP):

Phenol Antioxidants:

AO1. Tetrakismethylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate) methane(IRGANOX® 1010):

AO2. (1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (CYANOX® 1790):

AO3. 1,3,5-Tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate (IRGANOX®3114):

AO4. Triethylene glycol bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate] (IRGANOX® 245):

AO5. Di(4-tertiarybutyl-3-hydroxy-2,6-dimethyl benzyl) thiodipropionate:

Light Stabilizers:

LS1: 1,6-hexanediamine,N,N′-bis (2,2,6,6-tetramethyl)-4-piperidinyl)-,polymers with 2,4-dichloro-6-(4-morpholinyl)-1,3,5-triazine (CYASORB®UV-3346). LS1 is a HALS.

LS2:2-[4,6-bis(2′,4′-dimethylphenyl)-1,3,5-triazin-2-yl]-5-octyloxyphenol(CYASORB® UV-1164). LS2 is a UVA

LS3: 1,6-hexanediamine, N,N′-bis(1,2,2,6,6-pentamethyl)-4-piperidinyl)-,polymers with 2,4-dichloro-6-(4-morpholinyl)-1,3,5-triazine (CYASORB®UV-3529). LS3 is a HALS.

LS4: Dimethyl Succinate polymerw/4-Hydroxy-2,2,6,6-tetramethyl-1-piperidine ethanol (CAS No.65447-77-0). LS4 is a HALS.

In the examples, the following physical properties are measured bytechniques set forth in the corresponding ASTM standard:

Yellowness Index: ASTM E313, ASTM D6290

Melt Index: ASTM D1238, D2839

Weathering: ASTM G154

Impact Strength ARM Impact, ASTM D3029

Colorguard instrument: MacBeth Color-Eye 7000 Spectrophotometer

(Equation—Hunter Lab; Observer—2o; Primary Illuminant—C).

In certain embodiments, polymer compositions are made using rotationalmolding techniques that are generally accepted by those skilled in theart as being representative of commercial rotational molding processes.These rotational molding techniques involve the use of a rotational moldand an oven. A polymer composition (e.g., a stabilized polymercomposition comprising a stabilizer composition as described herein) isplaced in the mold, which possesses a predetermined shape. The mold isheated within the oven at a predetermined rate to a peak temperature.During heating, the resin melts and the mold is rotated in threedimensions to ensure that the melted resin evenly coats the interiorsurfaces of the mold. Optionally, the melted resin may be cured for apredetermined time. After heating is complete, the mold is removed fromthe oven and cooled, with the mold still in rotation. Once cool, theformed plastic part is removed from the mold.

Examples 1-12

Examples 1-12 illustrate the melt index and the color, as measured bythe yellowness index, of polymer compositions utilizing stabilizercompositions that contain reduced hindrance phenols and compare theseproperties to those of compositions that contain more highly hinderedphenols.

Exxon LL8400 grade of LLDPE is dry blended with about 350 ppm of zincstearate, about 1090 ppm of LS1, about 110 ppm of LS2, about 435 ppm ofP1, about 120 ppm of P2, and about 245 ppm of a phenolic antioxidant asshown in TABLES 1-3 below. The dry blend is extruded using a singlescrew extruder at a melt temperature of about 190° C. After measuringthe color of the pelletized resin using a Colorguard instrument, theresin is ground to a fine powder. About 10 g of resin is poured into anapproximately 5 cm×5 cm steel mold and placed on an open compressionmold platen at a set point temperature of about 300° C. for about 12minutes. After cooling to crystallization point at about ambienttemperature, the plaque is removed from the mold and the yellownessindex is measured on both the air and mold surface of the plaque. Theresults of these tests are reported in TABLES 1-3 below. TABLE 1provides the Yellowness Index (YI) values of the LLDPE pellets aftercompounding, TABLE 2 provides YI values of the plaques (side exposed toair and side in contact with mold), and TABLE 3 provides the Melt Index(MI) of the resin samples immediately after compounding and after theopen air sintering process. The resin had an initial MI of 3.3 g/10 min.

TABLE 1 No. Phenolic Antioxidant YI 1C AO1 0.23 2 AO4 −1.26 3C AO3 0.764 AO2 −1.54

TABLE 2 No. Phenolic Antioxidant YI (air) YI (mold) 5C AO1 16.7 2.7 6AO4 1.7 −1.3 7C AO3 12.7 3.1 8 AO2 0.83 −0.63

TABLE 3 Phenolic No. Antioxidant MI (after compounding) MI (aftersintering)  9C AO1 3.11 2.21 10 AO4 3.27 2.37 11C AO3 3.19 2.24 12 AO23.23 2.79

Examples 1-12 demonstrate that, in stabilizer compositions containingcombinations of P1 (of formula III) and P2 (of formula I), reducedhindrance phenols AO2 and AO4 (of formula IV) provide improved color inpellets and sintered resins, as compared to more highly hindered phenolsAO1 and AO3. As shown in TABLES 1-2, the yellowness index of polymersstabilized with combinations containing less hindered phenols issignificantly lower than polymers stabilized with combinationscontaining more highly hindered phenols. Thus, Examples 1-12 illustratethat stabilizer compositions containing a phosphite of formula I, atrisaryl phosphite of formula III, and a reduced hindrance phenol offormula IV provide generally superior color to otherwise similarstabilizer compositions containing more highly hindered phenols.

Examples 13-16

Examples 13-16 illustrate and compare the color of polymer compositionscontaining stabilizer compositions similar to those described inExamples 1-12, except without the light stabilizer compounds.

Exxon LL8400 grade of LLDPE is dry blended with approximately 350 ppm ofzinc stearate, approximately 435 ppm of P1, approximately 120 ppm of P2and approximately 245 ppm of a phenolic antioxidant. The dry blend isextruded using a single screw extruder at a melt temperature ofapproximately 190° C. After measuring the color of the pelletized resinusing a Colorguard instrument, the resin is ground to a fine powder.Approximately 10 g of resin is poured into an approximately 5 cm×5 cmsteel mold and placed on an open compression platen at a set pointtemperature of approximately 300° C. for approximately 12 minutes. Aftercooling to a crystallization point at approximately ambient temperature,the plaque is removed from the mold and the yellowness index is measuredon both the air and mold surface of the plaque. TABLE 4 provides the YIvalues of the pellets after compounding and TABLE 5 provides YI valuesof the plaques (side exposed to air and side in contact with mold).

TABLE 4 No. Phenolic Antioxidant YI 13C AO1 0.06 14 AO2 −1.92

TABLE 5 No. Phenolic Antioxidant YI (air) YI (mold) 15C AO1 4.62 0.6 16AO2 1.43 −0.75

Examples 13-16 demonstrate that polymers stabilized with combinationscontaining less hindered phenol antioxidants exhibit improved color. Asillustrated in TABLES 4 and 5, the color of polymer compositionscontaining phenol antioxidant AO1, a more highly hindered phenolantioxidant, are significantly higher than polymer compositionscontaining a phosphite of formula I, a trisaryl phosphite of formula IIIand AO2, a less hindered phenol antioxidant, in both pellet and sinteredresin forms. These trends are consistent with those shown in TABLES 1-3for Examples 1-12.

Examples 17-22

Examples 17-22 illustrate the effect of varying the ratio of P1 and P2on the color of polymer compositions containing P1, P2, and AO2. ExxonLL8400 grade of LLDPE is dry blended with about 350 ppm of zincstearate, about 1090 ppm of LS1, about 110 ppm of LS2, about 245 ppm ofAO2, and varying amounts of trisarylphosphites (P1) with pentaerythritolphosphites (P2). The dry blend is extruded using a single screw extruderwith a melt temperature of about 190° C. After measuring the color ofthe pelletized resin using a Colorguard instrument, the resin is groundto a fine powder. About 10 g of resin is poured into an approximately 5cm×5 cm steel mold and placed on an open compression platen at a setpoint temperature of about 300° C. for about 12 minutes. After coolingto crystallization point at about ambient temperature, the plaque isremoved from the mold and the color measured on both the air and moldsurface of the plaque. TABLE 6 provides the YI values of the pelletsafter compounding and TABLE 7 provides YI values of the plaques (sideexposed to air and side in contact with mold).

TABLE 6 No. P1 (ppm) P2 (ppm) YI 17 500 55 −1.74 18 435 120 −1.55 19 310245 −0.82

TABLE 7 No. P1 (ppm) P2 (ppm) YI (air) YI (mold) 20 500 55 10 3.6 21 435120 0.83 −0.6 22 310 245 4.37 1.19

Examples 17-22 illustrate that in stabilized polymer compositionscontaining trisarylphosphites (P1) and pentaerythritol phosphites (P2)in combination with reduced hindrance phenol antioxidants, it isgenerally preferred to have a lower ratio of P2 to P1 to provide lowcolor. As shown in TABLES 6 and 7, a general decrease is observed in theyellowness index of pelletized LLDPE as the proportion of P2 to P1decreases. In sintered powder resins, YI decreases as the P2 to P1 ratiodecreases to a ratio of about 1:4. Thus, Examples 17-22 illustratepolymer compositions in which preferred proportions of phosphiteantioxidants in combination with reduced hindrance phenol antioxidantsas polymer stabilizers provide improved color.

Examples 23-35

Lyondell 662-grade of LLDPE is dry blended with approximately 350 ppm ofzinc stearate, 1090 ppm of LS1, approximately 110 ppm of LS2,approximately 245 ppm of AO2 along with phosphite blends comprising atrisaryl phosphite (Phosphite A) and a pentaerythritol-based phosphite(Phosphite B) as specified in the tables below. The dry blend isextruded using a single screw extruder with a melt temperature ofapproximately 190° C. The extrudate is pelletized and the color of theresin measured directly on the pellets using a Colorguard instrument(TABLE 8). The pellets are then compression molded into plaques andexposed in a Q-Panel QUV accelerated weathering chamber. Color change ismeasured as a function of exposure time (TABLE 9). The pelletized resinis also ground to a fine powder. Approximately 10 g of resin is pouredinto an approximately 5 cm×5 cm steel mold and placed on a hot plate ata set point temperature of approximately 300° C. for approximately 10minutes. After cooling to the crystallization point at ambienttemperature, the plaque is removed from the mold and the color measuredon mold-side surface of the plaque (TABLE 10).

TABLE 8 Phosphite A Phosphite B No. (435 ppm) (120 ppm) YI 23C P1 P3−2.62 24 P1 P4 −2.62 25 P1 P2 −2.79 26 P1 P5 −2.62 27 P6 P2 −2.67

TABLE 9 Phosphite A Phosphite B No. (435 ppm) (120 ppm) Change in YI 28CP1 P3 1.7 29 P1 P4 1.1 30 P1 P2 1.1 31 P1 P5 1.4

TABLE 10 Phosphite A Phosphite B No. (435 ppm) (120 ppm) YI (mold) 32CP1 P3 −2.22 33 P1 P4 −2.95 34 P1 P2 −4.68 35 P1 P5 −5.14

Examples 23-35 illustrate that in stabilizer compositions containingcombinations of phosphites selected from the formulas I, II and III,along with a hindered phenol of the formula IV, it is preferable for thegroups flanking the oxygen atom attached to the aromatic ring in thephosphite of formula I or II to together comprise at least 5 carbonatoms.

Examples 36-37

Examples 36-37 illustrates stabilizer compositions containing acombination of phosphites of the formulas I and III along with ahindered phenol of the formula IV for rotational molding applications.

Hunstman LX131 LLDPE (octene comonomer) is dry blended with about 500ppm of calcium stearate, about 2000 ppm of LS3, about 300 ppm of AO2,about 600 ppm of P1, and about 100 ppm of a second phosphite as shown inTABLE 11 below. The dry blend is extruded using a single screw extruderwith a melt temperature of about 190° C. The resin is subsequentlyground to a fine powder. About 10 g of resin is poured into anapproximately 5 cm×5 cm steel mold and placed into an oven equilibratedat about 250° C. for about 9 minutes. After cooling to a crystallizationpoint at about ambient temperature, the plaque is removed from the moldand the color measured on both the air and mold surface of the plaque(TABLE 11).

TABLE 11 Second Phosphite No. (100 ppm) YI (air) YI (mold) 36C P3 −1.78−2.33 37 P2 −3.35 −3.79

Examples 36-37 demonstrate that stabilizer combinations containingphosphites of the formula I are preferable to otherwise similarstabilizer compositions in which the groups flanking the oxygen attachedto the aromatic ring of the phosphite contain less than 5 carbon atoms,particularly for rotational molding applications.

Examples 38-40

The color of stabilized polymer compositions containing reducedhindrance phenols in combination with phosphite antioxidants is measuredafter 10 and 15 minute cures of pelletized resins. Exxon LL8400 grade ofLLDPE is dry blended with approximately 350 ppm of zinc stearate,approximately 1090 ppm of LS1, approximately 110 ppm of LS2,approximately 435 ppm of P1, approximately 120 ppm of P2, andapproximately 245 ppm of a phenolic antioxidant. The dry blend isextruded using a single screw extruder with a melt temperature ofapproximately 190° C. The resin is subsequently ground to a fine powder.Approximately 10 g of resin is poured into an approximately 5 cm×5 cmsteel mold and placed on to a covered hotplate at a set pointtemperature of approximately 300° C. for 10 or 15 minutes. After coolingto a crystallization point at approximately ambient temperature, theplaque is removed from the mold and the color measured on surface of theplaque in contact with the metal mold (TABLE 12).

TABLE 12 Phenolic YI (mold) No. Antioxidant 10 min cure 15 min cure 38CAO3 −1.38 21.07 39 AO2 −4.04 5.94 40 AO5 −5.07 12.2

Examples 38-40 illustrate that reduced hindrance phenols are generallysuperior to more highly hindered phenols when used in combination withthe illustrated phosphite antioxidants.

Examples 41-44

Examples 41-44 measure and compare the yellowness index of stabilizedpolypropylene compositions containing reduced hindrance phenols andcompositions containing more highly hindered phenol antioxidants. BasellPH350 polypropylene homopolymer is dry blended with about 245 ppm of thespecified phenolic antioxidant, about 435 ppm of P1, about 120 ppm ofP2, and about 500 ppm CaSt. The dry blend is extruded using a singlescrew extruder with a melt temperature of the extruder maintained atabout 230° C. The extrudate is pelletized and the color of the resin ismeasured directly on the pellets using a Colorguard instrument (TABLE13)

TABLE 13 No. Phenolic Antioxidant YI 41C AO1 5.56 42 AO2 1.44 43C AO1 +1000 ppm LS2 4.06 44 AO2 + 1000 ppm LS2 1.43

Examples 41-44 illustrate that reduced hindrance phenol antioxidants aregenerally superior to more highly hindered phenol antioxidants forstabilizing polypropylene when used in combination with phosphites ofthe formulas I and III.

Examples 45-49

[Examples 45-49 illustrate the use of stabilizers containing compoundsof the formulas I, III, and IV to stabilize polymers in rotationalmolding applications. Exxon LL8400 grade of LLDPE is dry blended withapproximately 350 ppm of zinc stearate, an antioxidant, and lightstabilizers as shown in TABLES 14 and 15 below. The dry blend isextruded using a single screw extruder with a melt temperature ofapproximately 190° C. and ground to a fine powder of approximately 35mesh. About 1.5 kg aliquot of the powdered resin is then placed in anapproximately 1 ft×1 ft×1 ft mold which is rotated three dimensionallywhile heated in an oven at about 315° C. for about 13 or 15 minutes.After heating for the specified time, the mold is removed from the ovenand cooled. The hollow molded cube is then removed from the mold.Cutouts are taken from all faces of the cube and the color of each ismeasured on the outer and inner cube surfaces (TABLES 14 and 15).

These materials are further tested for impact strength. Following theabove outlined procedure, cutouts of approximately 5 inches×5 inches aretaken from all faces of the cube and these are tested for lowtemperature (−40° C.) impact strength according to the Association ofRotational Molders protocol (ASTM D3029) after approximately 13 and 15minute cure times (TABLE 16).

TABLE 14 (13 Minute Oven Cure Time) No. Composition YI (inner wall) YI(outer wall) 45C 350 ppm AO3 3.6 3.0 1000 ppm P1 1365 ppm LS4 200 ppmLS2 46C 350 ppm AO3 5.7 4.5 500 ppm P2 1090 ppm of LS1 110 ppm of LS2 47245 ppm AO2 0.7 0.5 435 ppm P1 120 ppm P2 1090 ppm of LS1 110 ppm of LS2

TABLE 15 (15 Minute Oven Cure Time) No. Composition YI (inner wall) YI(outer wall) 48C 350 ppm AO3 9.3 7.9 1000 ppm P1 1365 ppm LS4 200 ppmLS2 49 245 ppm AO2 4.4 3.4 435 ppm P1 120 ppm P2 1090 ppm of LS1 110 ppmof LS2

TABLE 16 Impact Strength Impact Strength No. Composition 13 min curetime 15 min cure time 50C 350 ppm AO3 48 ft-lbs <8 ft-lbs 1000 ppm P11365 ppm LS4 200 ppm LS2 51 245 ppm AO2 44 ft-lbs 44 ft-lbs 435 ppm P1120 ppm P2 1090 ppm of LS1 110 ppm of LS2

Examples 52-80 below illustrate methods of making stabilizercompositions suitable for incorporation into polyolefins and otherpolymers.

Examples 52-55

In Examples 52-55, P1, P2, and AO2, in the approximate amounts shown inTABLE 17 below, are dry blended to provide a stabilizer composition inthe form of a free flowing additive blend having the relative weightpercentages given in TABLE 18, suitable for dosing into polyolefins andother polymers.

TABLE 17 No. AO2 (grams) P1 (grams) P2 (grams) P1/P2 (wt. ratio) 52 245435 120 78/22 53 250 525 75 87.5/12.5 54 250 400 200 67/33 55 250 350250 58/42

TABLE 18 No. 52 53 54 55 wt. wt. wt. wt. (g) wt % (g) wt % (g) wt % (g)wt % HALS 0 0.00 0 0.00 0 0.00 0 0.00 UVA 0 0.00 0 0.00 0 0.00 0 0.00 AO245 30.63 250 29.41 250 29.41 250 29.41 P1 435 54.38 525 61.76 400 47.06350 41.18 P2 120 15.00 75 8.82 200 23.53 250 29.41 Other 0 0.00 0 0.00 00.00 0 0.00 Total 800 850 850 850

Examples 56-59

P1, P2, and AO2, in the approximate amounts shown in TABLE 19 below, aremeasured into a ribbon blender and then mixed to form a substantiallyhomogeneous powder composition. The relative weight percentages of thecomponents of the resulting stabilizer composition are given in TABLE20. This powder composition is then compacted to provide a stabilizercomposition in the form of a granular additive composition suitable forincorporation into polyolefins and other polymers.

TABLE 19 No. AO2 (kg) P1 (kg) P2 (kg) P1/P2 (wt. ratio) 56 245 435 12078/22 57 250 525 75 87.5/12.5 58 250 400 200 67/33 59 250 350 250 58/42

TABLE 20 No. 56 57 58 59 wt. wt. wt. wt. (g) wt % (g) wt % (g) wt % (g)wt % HALS 0 0.00 0 0.00 0 0.00 0 0.00 UVA 0 0.00 0 0.00 0 0.00 0 0.00 AO245 30.63 250 29.41 250 29.41 250 29.41 P1 435 54.38 525 61.76 400 47.06350 41.18 P2 120 15.00 75 8.82 200 23.53 250 29.41 Other 0 0.00 0 0.00 00.00 0 0.00 Total 800 850 850 850

Examples 60-63

Approximately 1000 kg of LS1 and approximately 110 kg of LS2 arecombined with P1, P2, and AO2 in approximately the amounts specified inTABLE 21 below. These components are added into a ribbon blender andmixed to form a substantially homogeneous powder blend. The relativeweight percentages of components of the resulting stabilizer compositionare given in TABLE 22 below. This powder blend is then compacted toafford a stabilizer composition in the form of a granular additive blendsuitable for dosing into polyolefins and other polymers.

TABLE 21 No. AO2 (kg) P1 (kg) P2 (kg) P1/P2 (wt. ratio) 60 245 435 12078/22 61 250 525 75 87.5/12.5 62 250 400 200 67/33 63 250 350 250 58/42

TABLE 22 No. 60 61 62 63 wt. wt. wt. wt. (g) wt % (g) wt % (g) wt % (g)wt % LS1 1000 52.36 1000 51.02 1000 51.02 1000 51.02 LS2 110 5.76 1105.61 110 5.61 110 5.61 AO 245 12.83 250 12.76 250 12.76 250 12.76 P1 43522.77 525 26.79 400 20.41 350 17.86 P2 120 6.28 75 3.83 200 10.20 25012.76 Other 0 0.00 0 0.00 0 0.00 0 0.00 Total 1910 1960 1960 1960

Examples 64-67

About 350 g of zinc stearate, about 1000 kg of LS1, and about 110 kg ofLS2 are combined with P1, P2, and AO2 in about the amounts specified inTABLE 23 below. These components are added into a ribbon blender andmixed to form a substantially homogeneous powder composition. Therelative weight percentages of components of the resulting stabilizercomposition are given in TABLE 24 below. This powder composition is thencompacted to provide a stabilizer composition in the form of a granularcomposition suitable for dosing into polyolefins and other polymers.

TABLE 23 No. AO2 (kg) P1 (kg) P2 (kg) P1/P2 (wt. ratio) 64 245 435 12078/22 65 250 525 75 87.5/12.5 66 250 400 200 67/33 67 250 350 250 58/42

TABLE 24 No. 64 65 66 67 wt. wt. wt. wt. (g) wt % (g) wt % (g) wt % (g)wt % LS1 1000 44.25 1000 43.29 1000 43.29 1000 43.29 LS2 110 4.87 1104.76 110 4.76 110 4.76 AO 245 10.84 250 10.82 250 10.82 250 10.82 P1 43519.25 525 22.73 400 17.32 350 15.15 P2 120 5.31 75 3.25 200 8.66 25010.82 Other 350 15.49 350 15.15 350 15.15 350 15.15 Total 2260 2310 23102310

Examples 68-70

Approximately 450 grams of P1 (75% of total phosphite) and approximately150 g of P2 (25% of total phosphite) are intermixed with approximately250 g of an antioxidant as specified in TABLE 25 below. The relativeweight percentages of components of the resulting stabilizer compositionare given in TABLE 26 below. Each composition is dry blended to afford astabilizer composition in the form of a free flowing additive blendsuitable for dosing into polyolefins and other polymers.

TABLE 25 No. Antioxidant 68 AO2 69 AO4 70 Octadecyl3-(3′-t-butyl-4′-hydroxy- 5′-methylphenyl)propionate

TABLE 26 No. 68-70 wt. (g) wt % HALS 0 0.00 UVA 0 0.00 AO 250 29.41 P1450 52.94 P2 150 17.65 Other 0 0.00 Total 850

Examples 71-75

About 450 grams of P1 (75% of total phosphite) and about 150 g of P2(25% of total phosphite) are combined with varying amounts of AO2 ofabout the weights specified in TABLE 27 below. The relative weightpercentages of the components of the stabilizer composition are given inTABLE 28 below. Each composition is dry blended to afford a stabilizercomposition in the form of a free flowing additive composition suitablefor compaction or dosing directly into a polyolefin or other polymer.

TABLE 27 Grams of Ratio of total No. AO2 phosphite to phenol 71 60 10:1 72 200 3:1 73 600 1:1 74 1200 1:2 75 1800 1:3

TABLE 28 No. 71 72 73 74 75 wt. wt. wt. wt. wt. (g) wt % (g) wt % (g) wt% (g) wt % (g) wt % HALS 0 0.00 0 0.00 0 0.00 0 0.00 0 0.00 UVA 0 0.00 00.00 0 0.00 0 0.00 0 0.00 AO 60 9.09 200 25.00 600 50.00 1200 66.67 180075.00 P1 450 68.18 450 26.25 450 37.50 450 25.00 150 18.75 P2 150 22.73150 18.75 150 125.00 150 8.33 150 6.25 Other 0 0.00 350 0.00 0 0.00 00.00 0 0.00 Total 660 800 1200 1800 2400

Examples 76-80

Approximately 1000 g of polyethylene is blended with varying amounts ofapproximately the weight of the stabilizer composition described inExample 71. The relative weight percentages of the components of thestabilizer composition are given in TABLE 29 below. The compositions arecompounded using a single screw extruder and pelletized to givestabilized polyethylene pellets containing ppm levels of additives asspecified in TABLE 29 below.

TABLE 29 Stabilizer Composition Concentration of No. (Example 71, g)P1/P2/AO2 (ppm) 76 0.5 281/94/125 77 1.5 843/281/375 78 3 1686/562/75079 6 3372/1124/1500 80 12 6744/2248/3000

Although the foregoing description has shown, described, and pointed outthe fundamental novel features of the present teachings, it will beunderstood that various omissions, substitutions, and changes in theform of the detail of the apparatus as illustrated, as well as the usesthereof, may be made by those skilled in the art, without departing fromthe scope of the present teachings. Consequently, the scope of thepresent teachings should not be limited to the foregoing discussion, butshould be defined by the appended claims.

1. A stabilizer composition, comprising: (a) a hindered arylalkylphosphite of the formula (I) or (II),

wherein R¹ and R⁵ together comprise at least 5 carbons and at least oneof R¹ and R⁵ comprises a tertiary carbon; wherein R⁶ and R¹⁰ togethercomprise at least 5 carbons and at least one of R⁶ and R¹⁰ comprises atertiary carbon; wherein R¹¹ and R¹⁵ together comprise at least 5carbons and at least one of R¹¹ and R¹⁵ comprises a tertiary carbon;wherein R¹, R², R³, R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴,R¹⁵, X and Y are each individually selected from hydrogen, C₁-C₁₂ alkyl,C₃-C₁₂ cycloalkyl, C₄-C₁₂ alkyl cycloalkyl, C₆-C₁₀ aryl, and C₇-C₁₂alkylaryl; (b) a trisarylphosphite of the formula (III),

wherein R¹⁶, R¹⁷, R¹⁸, R¹⁹, and R²⁰ are each individually selected fromhydrogen, C₁-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₄-C₂₀ alkyl cycloalkyl,C₆-C₁₀ aryl, and C₇-C₂₀ alkylaryl; and (c) a hindered phenol comprisinga molecular fragment selected from formulas (IVa), (IVb) and (IVc),

wherein R²¹ is selected from hydrogen and C₁₋₃ alkyl; and wherein R²²and R²³ are each individually selected from hydrogen, C₁-C₂₀ alkyl,C₃-C₂₀ cycloalkyl, C₄-C₂₀ alkyl cycloalkyl, C₆-C₁₀ aryl, and C₇-C₂₀alkylaryl.
 2. A stabilizer composition according to claim 1, wherein R¹and R⁵ together comprise at least 8 carbons.
 3. A stabilizer compositionaccording to claim 1, wherein R¹ is H.
 4. A stabilizer compositionaccording to claim 1, wherein R⁵ is cumyl.
 5. A stabilizer compositionaccording to claim 1, wherein R²¹ is methyl.
 6. A stabilizer compositionaccording to claim 1, wherein the weight ratio of the hindered arylalkylphosphite to the trisarylphosphite is less than 1:1.
 7. A stabilizercomposition according to claim 1, wherein the weight ratio of thehindered arylalkyl phosphite to the trisarylphosphite is in the range offrom about 1:15 to about 4:5.
 8. A stabilizer composition according toclaim 1, wherein the weight ratio of the hindered arylalkyl phosphite tothe trisarylphosphite is in the range of from about 1:10 to about 2:3.9. A stabilizer composition according to claim 1, wherein the hinderedarylalkyl phosphite is selected from 2-butyl-2-ethyl-1,3-propanediol2,4,6-tri-t-butylphenol phosphite,bis-(2,6-di-t-butyl-4-methlphenyl)pentaerythritol diphosphite,(bis-(2,4-dicumylphenyl)pentaerythritol diphosphite,2-butyl-2-ethyl-1,3-propanediol 2,4-dicumylphenol phosphite,2-butyl-2-ethyl-1,3-propanediol 4-methyl-2,6-di-t-butylphenol phosphite,and bis-(2,4,6-tri-t-butyl-phenyl)pentaerythritol diphosphite.
 10. Astabilizer composition according to claim 1, wherein thetrisarylphosphite is selected from tris-(2,4-di-t-butylphenyl)phosphite,tris(4-nonylphenyl phosphite and triphenyl phosphite.
 11. A stabilizercomposition according to claim 1, wherein the hindered phenol isselected from (1,3,5-Tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione,1,1,3-Tris(2′-methyl-4′-hydroxy-5′-t-butylphenyl)butane, Triethyleneglycol bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate],4,4′-Thiobis (2-t-butyl-5-methylphenol), 2,2′-Thiodiethylenebis[3-(3-t-butyl-4-hydroxyl-5-methylphenyl)propionate], Octadecyl3-(3′-t-butyl-4′-hydroxy-5′-methylphenyl)propionate,Tetrakismethylene(3-t-butyl-4-hydroxy-5-methylhydrocinnamate)methane,N,N′-Hexamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionamide], andDi(4-tertiarybutyl-3-hydroxy-2,6-dimethyl benzyl) thiodipropionate. 12.A polymer composition, comprising a polymer and a stabilizing amount ofa stabilizer composition according to claim
 1. 13. A polymer compositionaccording to claim 12, wherein the polymer comprises a polyolefin.
 14. Apolymer composition according to claim 12, wherein the stabilizingamount of the stabilizer composition is in the range of from about 0.01%to about 1.0%, by weight based on the total weight of the polymercomposition.
 15. A polymer composition according to claim 12, whereinthe amount of the hindered arylalkyl phosphite in the polymercomposition is less than the amount of the trisarylphosphite on a weightbasis.
 16. A polymer composition according to claim 12, wherein thehindered arylalkyl phosphite and the trisarylphosphite are togetherpresent in a total phosphite amount in the range of about 0.01 wt. % toabout 1.0 wt %, based on total polymer composition weight.
 17. A polymercomposition according to claim 12, wherein the hindered arylalkylphosphite and the trisarylphosphite are together present in a totalphosphite amount in the range of about 0.02 wt. % to about 0.5 wt %,based on total polymer composition weight.
 18. A polymer compositionaccording to claim 12, wherein the stabilizing amount of the stabilizercomposition is an amount that is effective to reduce yellowing of thepolymer.
 19. A polymer composition according to claim 12, wherein thehindered arylalkyl phosphite is selected from2-butyl-2-ethyl-1,3-propanediol 2,4,6-tri-t-butylphenol phosphite,bis-(2,6-di-t-butyl-4-methlphenyl) pentaerythritol diphosphite,(bis-(2,4-dicumylphenyl)pentaerythritol diphosphite,2-butyl-2-ethyl-1,3-propanediol 2,4-di-cumylphenol phosphite,2-butyl-2-ethyl-1,3-propanediol 4-methyl-2,6-di-t-butylphenol phosphite,and bis-(2,4,6-tri-t-butyl-phenyl) pentaerythritol diphosphite.
 20. Apolymer composition according to claim 12, wherein the trisarylphosphiteis selected from tris-(2,4-di-t-butylphenyl) phosphite,tris(4-nonylphenyl phosphite and triphenyl phosphite.
 21. A polymercomposition according to claim 12, wherein the hindered phenol isselected from (1,3,5-Tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione,1,1,3-Tris(2′-methyl-4′-hydroxy-5′-t-butylphenyl)butane, Triethyleneglycol bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate],4,4′-Thiobis (2-t-butyl-5-methylphenol), 2,2′-Thiodiethylenebis[3-(3-t-butyl-4-hydroxyl-5-methylphenyl)propionate], Octadecyl3-(3′-t-butyl-4′-hydroxy-5′-methylphenyl)propionate,Tetrakismethylene(3-t-butyl-4-hydroxy-5-methylhydrocinnamate)methane,N,N′-Hexamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionamide], andDi(4-tertiarybutyl-3-hydroxy-2,6-dimethyl benzyl) thiodipropionate. 22.A polymer composition according to claim 12, further comprising a lightstabilizer selected from a hindered amine light stabilizer, a hinderedhydroxyl benzoate, a nickel phenolate, and an ultraviolet lightabsorber.
 23. A polymer composition according to claim 22, wherein thelight stabilizer is a hindered amine light stabilizer.
 24. A polymercomposition according to claim 23, wherein the hindered amine lightstabilizer comprises a molecular fragment of the formula (V),

wherein R²⁴, R²⁵, R²⁶, and R²⁷ are each individually selected fromhydrogen, C₁-C₂₀ alkyl, C₃-C₂₀ cycloalkyl, C₄-C₂₀ alkyl cycloalkyl,C₆-C₁₀ aryl, and C₇-C₂₀ alkylaryl; and wherein R²⁸ is selected fromhydrogen, C₁-C₂₀ alkyl, C₁-C₂₀ acyl and C₁-C₂₀ alkoxyl.
 25. A polymercomposition according to claim 23, wherein the hindered amine lightstabilizer is selected frombis(2,2,6,6-tetramethylpiperidin-4-yl)sebacate;bis(2,2,6,6-tetramethylpiperidin-4-yl)succinate;bis(1,2,2,6,6-pentamethylpiperidin-4-yl)sebacate;bis(1-octyloxy-2,2,6,6-tetramethylpiperidin-4-yl)sebacate;bis(1,2,2,6,6-pentamethylpiperidin-4-yl) n-butyl3,5-di-tert-butyl-4-hydroxybenzylmalonate; a condensate of1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinicacid; 2,2,6,6-tetramethylpiperidin-4-yl stearate;2,2,6,6-tetramethylpiperidin-4-yl dodecanate;1,2,2,6,6-pentamethylpiperidin-4-yl stearate;1,2,2,6,6-pentamethylpiperidin-4-yl dodecanate; a condensate ofN,N′-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine and4-tert-octylamino-2,6-dichloro-1,3,5-triazine;tris(2,2,6,6-tetramethylpiperidin-4-yl) nitrilotriacetate; tetrakis(2,2,6,6-tetramethylpiperidin-4-yl)-1,2,3,4-butanetetracarboxylate;4-benzoyl-2,2,6,6-tetramethylpiperidine;4-stearyloxy-2,2,6,6-tetramethylpiperidine;bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3,5-di-tert-butylbenzyl)malonate;3-n-octyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decan-2,4-dione;bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)sebacate;bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl)succinate; a condensate ofN,N′-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine and4-morpholino-2,6-dichloro-1,3,5-triazine; a condensate of2-chloro-4,6-bis(4-n-butylamino-2,2,6,6-tetramethylpiperidyl)-1,3,5-triazineand 1,2-bis(3-aminopropylamino)ethane; a condensate of2-chloro-4,6-bis(4-n-butylamino-1,2,2,6,6-pentamethylpiperidyl)-1,3,5-triazineand 1,2-bis-(3-aminopropylamino)ethane;8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro[4.5]decane-2,4-dione;3-dodecyl-1-(2,2,6,6-tetramethylpiperidin-4-yl)pyrrolidin-2,5-dione;3-dodecyl-1-(1-ethanoyl-2,2,6,6-tetramethylpiperidin-4-yl)pyrrolidin-2,5-dione;3-dodecyl-1-(1,2,2,6,6-pentamethylpiperidin-4-yl)pyrrolidine-2,5-dione;a mixture of 4-hexadecyloxy- and4-stearyloxy-2,2,6,6-tetramethylpiperidine; a condensate ofN,N′-bis(2,2,6,6-tetramethylpiperidin-4-yl)hexamethylenediamine and4-cyclohexylamino-2,6-dichloro-1,3,5-triazine; a condensate of1,2-bis(3-aminopropylamino)ethane, 2,4,6-trichloro-1,3,5-triazine and4-butylamino-2,2,6,6-tetramethylpiperidine;2-undecyl-7,7,9,9-tetramethyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decane;oxo-piperanzinyl-triazines and a reaction product of7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8-diaza-4-oxospiro[4.5]decaneand epichlorohydrin.
 26. A polymer composition according to claim 23,further comprising an ultraviolet light absorber.
 27. A polymercomposition according to claim 22, wherein the light stabilizer is anultraviolet light absorber.
 28. A polymer composition according to claim26, wherein the ultraviolet light absorber is selected from a2-hydroxybenzophenone, a 2-(2′-hydroxyphenyl)benzotriazole, and a2-(2′-hydroxyphenyl)-1,3,5-triazine.
 29. A polymer composition accordingto claim 28, wherein the 2-(2′-hydroxyphenyl)-1,3,5-triazine is of theformula (VI),

wherein R²⁹ and R³⁰ are each individually selected from C₆-C₁₀ aryl,C₁-C₁₀ alkyl-substituted amino, C₁-C₁₀ acyl and C₁-C₁₀ alkoxyl; and R³¹,R³², R³³ and R³⁴ are each individually selected from hydrogen, hydroxyl,C₁-C₁₀ alkyl, C₁-C₁₀ alkoxyl, C₁-C₁₀ acyl, C₃-C₁₂ cycloalkyl, C₄-C₁₂alkyl cycloalkyl, C₆-C₁₀ aryl, and C₇-C₁₂ alkylaryl.
 30. A polymercomposition, comprising: a polyolefin; a polyolefin-stabilizing amountof a hindered arylalkyl phosphite selected from2-butyl-2-ethyl-1,3-propanediol 2,4,6-tri-t-butylphenol phosphite,bis-(2,6-di-t-butyl-4-methlphenyl)pentaerythritol diphosphite,(bis-(2,4-dicumylphenyl)pentaerythritol diphosphite,2-butyl-2-ethyl-1,3-propanediol 2,4-dicumylphenol phosphite,2-butyl-2-ethyl-1,3-propanediol 4-methyl-2,6-di-t-butylphenol phosphite,and bis-(2,4,6-tri-t-butyl-phenyl)pentaerythritol diphosphite; apolyolefin-stabilizing amount of a trisarylphosphite selected fromtris-(2,4-di-t-butylphenyl)phosphite, tris(4-nonylphenyl phosphite andtriphenyl phosphite; and a polyolefin-stabilizing amount of a hinderedphenol selected from(1,3,5-Tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione,1,1,3-Tris(2′-methyl-4′-hydroxy-5′-t-butylphenyl)butane, Triethyleneglycol bis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionate],4,4′-Thiobis (2-t-butyl-5-methylphenol), 2,2′-Thiodiethylenebis[3-(3-t-butyl-4-hydroxyl-5-methylphenyl)propionate], Octadecyl3-(3′-t-butyl-4′-hydroxy-5′-methylphenyl)propionate,Tetrakismethylene(3-t-butyl-4-hydroxy-5-methylhydrocinnamate)methane,N,N′-Hexamethylenebis[3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionamide], andDi(4-tertiarybutyl-3-hydroxy-2,6-dimethyl benzyl) thiodipropionate. 31.A process for making a stabilized polymer composition, comprising mixinga polymer with a stabilizing amount of a stabilizer compositionaccording to claim
 1. 32. The process of claim 31, wherein the polymercomprises a polyolefin.
 33. The process of claim 31, comprising formingthe stabilizer composition in the presence of the polymer.
 34. Theprocess of claim 33, wherein the mixing comprises at least one selectedfrom extruding, pelletizing and molding.
 35. The process of claim 34,wherein the molding comprises at least one selected from blow molding,injection molding and rotational molding.
 36. The process of claim 31,further comprising mixing the polymer and the stabilizer compositionwith a light-stabilizing amount of a hindered amine light stabilizer.37. The process of claim 35, further comprising mixing the polymer andthe stabilizer composition with a light-stabilizing amount of anultraviolet light absorber selected from a 2-hydroxybenzophenone, a2-(2′-hydroxyphenyl)benzotriazole, and a2-(2′-hydroxyphenyl)-1,3,5-triazine.